A digital camera captures an image of a particular subject using an imaging system that includes an optical lens and a photosensor array, such as a charged coupled device (CCD). The imaging system “captures” a set, or frame, of digital image data that represents a particular subject at the time that the frame is captured. Each frame of digital image data can be stored in a memory for subsequent viewing on a display, printing onto paper, or downloading to a computer system. Because of the inherent space limitations of a hand-held digital camera, memory capacity for storing frames of digital image data within the camera is limited.
In addition to having storage capability, hand-held digital cameras are able to process digital image data to enhance the resolution and overall quality of an image that is presented to a viewer. In order to perform increasingly complex image enhancements, additional processing capability is required on-board a hand-held digital camera, but because of the inherent space limitations of hand-held digital cameras, processing capability is limited.
Hand-held digital cameras are available in which a still image of a subject can be viewed from a display device located within the hand-held digital camera. In hand-held digital cameras with image display capability, the problems of memory and processing limitations are magnified.
One technique used to overcome the memory limitations of hand-held digital cameras is disclosed in U.S. Pat. No. 5,534,921, entitled “CCD Digital Camera System With Selectable Memories,” issued to Sawanobori. In the Sawanobori patent, a detachable memory card is inserted into a hand-held digital camera and digital image data is transferred to the memory card. When the storage capacity of the memory card is reached, the memory card can be removed from the camera and replaced with a new memory card. A concern with the Sawanobori technique is that the memory cards themselves have limited storage capacity. A second concern is that the memory cards must be manually replaced when memory capacity is reached, creating a delay and a distraction to the operator of a hand-held digital camera.
Another technique that is employed to address the memory limitations of hand-held digital cameras is disclosed in U.S. Pat. No. 5,402,170 entitled “Hand-Manipulated Electronic Camera Tethered To A Personal Computer,” issued to Parulski et al. (hereinafter '170). In the '170 patent, an electronic camera is linked to a computer by a cable and an interface protocol is utilized to allow the camera to transmit image data over the cable and into a memory device of the computer. Disadvantages of the technique are that the hand-held digital camera must be “tethered” to the computer by a cable in order to accomplish data storage and that the technique only allows data transfer in one direction, from the camera to the computer, eliminating the possibility of viewing previously stored images on the display device of the hand-held digital camera.
A technique for overcoming the memory limitations involving the wireless transmission of electronic image data from an electronic hand-held camera is disclosed in U.S. Pat. No. 5,666,159, entitled “Electronic Camera System With Programable Transmission Capability,” issued to Parulski (hereinafter '159). In the '159 patent, an electronic camera is detachably coupled to a portable computer that has a display module and a radio-frequency transmitter module. The system is able to transmit electronic image data to a selected base unit using standard wireless communications techniques. While the technique is intended to be used to send facsimile images of a subject to a fax machine, the technique can be adapted to allow corresponding facsimile image data to be stored in a properly equipped computer. A disadvantage of the technique is that image data is transferred in only one direction, from the camera/computer combination to a base unit. Another example of a wireless transmission technique used to transmit electronic image data is disclosed in U.S. Pat. No. 5,475,441, entitled “Electronic Camera With Memory Card Interface To A Computer,” issued to Parulski et al (hereinafter '441). In the '441 patent, electronic image data is transmitted from an electronic hand-held camera with no display capability to a computer via a wireless transmission link. The computer that receives the data is relied upon to perform image processing, image data storage, and image display. While the '441 patent provides a high speed interface for transferring image data from a hand-held camera to a computer, a disadvantage of the '441 patent is that the hand-held camera does not have image display capability and the interface does not allow image data that is stored on the computer to be transmitted back to the hand-held camera for viewing.
What is needed is a hand-held digital camera system that has a built-in image display device and high capacity image data storage. In addition, what is need is a hand-held digital camera system that can display high quality images for viewing immediately after an image is captured.